I don't know which model SeaDoo you have, but check the owners manual (If you don't have it, download it). It will probably tell you that you need to use a 2-stroke oil that is rated API-TC, which your AMSOIL Interceptor is!
The Pennzoil however is NOT. TCW-3 is a lower rated oil then API-TC, also TCW-3 is typically 'ashless' where as APT-TC is typically "low ash".
Some people will tell you they've run TCW-3 in their SeaDoo's for 100 years with out ever a fail, My question is do you want to chance it?
You should check out
Mystik JT-4 PWC Oil, it is API-TC rated and is only about $25/gal. If you can find it locally you can probably find it for $20-$22/gal.
You of course are free to run whatever you want in your ski's, but I definitly would atleast run an oil with the rating the manufacture suggests.
In reguards to your oil pump delete, The SeaDoo oil pumps have a VERY good rep for being great oil pumps, most reports you hear about get blaimed on the oil pump when 99% of the time it wasn't the oil pump, but the oil lines from the oil pump that failed. (Which is a maintaince item and should be blamed on the owner, not the pump or manufacture). If you check the lines for cracking, and make sure the oil lines are in good shape you shouldn't have ANY problems with a SeaDoo oil pump. The injection system is a variable system and works much better then pre-mix.
HTH
-TheChad